The invention relates to a system for producing cables, comprising an extrusion apparatus with one or a plurality of extruders and a cross head through which the line or lines for the cable pass and after which an induction heating apparatus is arranged, whereby downstream of the cross head and the induction heating apparatus downstream thereof, for cross-linking and/or vulcanization of the extruded jacket layer, is a tube that constitutes a plurality of tube pieces, of which the tube piece adjacent to the cross head is a telescoping tube enabling access to the cross head.
The core of the cable comprises one or a plurality of copper wires that are surrounded by insulating and/or semiconductor layers that are fed by the extruder or extruders to the head and in the head are molded into the insulating layers covering the line or lines.
Such a system has become known from various previous uses. In the vulcanization tube downstream of the head, the freshly produced cable leaving the head must be maintained for a certain time at a temperature above the vulcanization temperature of the extruded layers. This occurs from the exterior using radiation and using the hot, primarily gaseous medium situated in the vulcanization tube. The vulcanization tube can be a suspended tube extending in the horizontal direction like a catenary curve; it can also be a vertically positioned tube, if necessary with a 180° reversing site.
With the induction heating, the core of the cable is heated to a temperature above the vulcanization temperature so that the heat required for vulcanization is also carried into the insulating layers from the interior. This heat carried in by induction thus reduces the time required for heating the entire cross-section of the cable to the vulcanization temperature and thus also reduces the structure length of the vulcanization tube. Every possible reduction in the length of the vulcanization tube increases the efficiency of the cable producing system, reduces capital costs, not only for the system but also for the workshop, and simplifies its operation.